I prefer to use a large neck roast for this recipe, but you could of course use other cuts, like a shank or a shoulder or even a hind leg roast. The long slow simmer melts all the connective tissue in the neck and gives you an intensely flavored, yielding piece of meat to either tear apart roughly or slice thick and serve. Note that a boned-out neck will be sliceable, but not in clean cuts unless you chill the meat overnight before slicing. Why bother with that, though? Eat it messy.
Bring the wine, allspice, black peppercorns and bay leaves to a boil. Turn off the heat and let the marinade cool to room temperature. When it’s cool, submerge the venison neck in the marinade and keep in the fridge overnight, or up to 4 days.
Mix the flour, paprika and cayenne (if using) together in a large bowl or shallow container large enough to hold the neck roast. Pat the meat dry with paper towels and salt it well. Coat it in the flour-paprika mixture. Heat the lard in a large Dutch oven or other heavy, lidded pot and brown the meat. With a typical neck roast you will need to cut it into two pieces to get it to fit the pot. Brown one piece and then remove while you brown the other. If you are using a bone-in neck, just turn the meat to brown all sides. When the meat has browned, remove it from the pot and set aside for a moment.
Preheat the oven to 325°F. Add the sliced onions to the pot and brown them well, stirring occasionally. This should take about 8 minutes. Add 2 cups of the marinade and bring it to a boil. Add the venison back to the pot, along with 2 cups of water. Bring to a simmer, cover the pot and cook in the oven for 1 1/2 hours.
After 1 1/2 hours have elapsed, add the root vegetables and celery and continue to cook for another 1 ½ hours, or until the meat is falling apart and the root vegetables are tender.
Remove the meat and set on a cutting board. Slice roughly or pull the meat off the bones. Taste the sauce and add salt if it needs it. Add black pepper to taste and serve with the meat and vegetables, with a dollop of sour cream alongside.